Device for gauging recess diameters



June 17, 1952 H. A. HAMERLY EI'AL 2,600,498

DEVICE FOR GAUGING RECESS DIAMETERS 3 Sheets-Sheet 1 Filed Feb. 27, 1948 fnv'eniofa'" Hugo Q. fi amer jgymur June 17, 1952 H. A. HA MERLY ETAL 2,600,493

DEVICE FOR GAUGING RECESS DIAMETERS Filed Feb. 27, 1948 3 Sheets-Sheet 2 fnvenforii H 21 90 a. fiizmery and; jqymaurfifwrz 'gkz June 17, 1952 H. A. HAMERL Y ETAL 2,600,498

DEVICE FOR 'GAUGING RECESS DIAMETERS w i 3? (57 I l I L 32 is Patented June 17, 1952 s m-ates 2,600,458 i DEVICE FOR GAUGING RECEsfSZDI AME IERs ringe Ha ma swear)iif iv aittiximcage, 111;; said Wright assignor to said Hainrly I fipiilicatidnTbiuary 27, 1154s; seiiai Mil i-$87 4 -10 Clainis.

i This inventionrelates :to 'aigauge device :m'ore il-particularly for determining "the depth or diame- -ter or both of center recesses in machine-turned articles such its "of- Cylindrical :shape in the production of whichgth'e article isheld by' a center "ata"eetc:h end while being machined by the usual -to'ol-af0r that-purpose. t V

' Since vthe article is "located o'n the: centerseby rmeans ofi'the centr'recesses at eache'end-of-the article, tliese :rece'sses being .conoidal to cor- -res'pnn'd with the conoid'alr-poin'tsiofqthe:center relen'i'ents,fgreat accuracy -is Tnece'ssary i'nxthe forming of the center recesses to permit accurate machining for high "precision ewo'rk. v, v The invention provides a xgauge device fo'r measuring the diametersof figures with reference tif'which the-diameter-to be measured is the base of an isosceles triangle; the device including "a z-gauge;pinfadapted to travel ia distance equal to g an elementsof -the' triangle-and means for trans- Hating the distance. of movement .of the gauge pin into measurement on an instrument of the: said diameter, said means including mechanism,- having 5cerr e1ated parts related in: a :ratio predes term-ined by'r-a tri-go'nometric function of anengle (ifz-thei'isosceles triangle. v e c c.

E-"As is wellknown, the center points and correspondingly the center d'einiessions usually-defi-n'e cones: of 60 degrees taper. .xIt, is. also jfwell "-knot'ifn that 'afplane perpendicular-to the axis of s1ich aonefdefines along" thezplaneof thehaxis, K a-ni isosceles triang'le in cross-section, and in-fthe c'ase'di iat 60 coneiian=equilateraltrianglefithe line iiiefpendicular to the axis representing .1311 ielement of the triangle such as thebasefof theatriangle and the :axis representing an element 6f .itlieitriang le Isuchaas thealtit'ude ;-of, the triangle.

'It: i-s-- also -welltknown hy the: laws {of trigonometry thatZthelerigthvjf'the altitude of anisoscelesatriang'le bears a iixe'direlation tc the lengths or .rthe

.base', 01f' 'in otheriwords is a constant, ior'ai-given included angle at the apex. at c V v J Starting this-another way, the tangentiof a is 5:274. 1 clonsequentlyf by measuring the depth df 2231 60- centerreeesswflor altitude of the triangle) zand'multiplying; this; by twice .5714, the diameter 9t :i hee ec s e ba e o t e t ia e) at the iplane -of the 'end surface of =the -articIe-m'ay'be u d- .w .n Among other objects :the present invention imS't FD fOV E ef mpecti-nexp m ve, nd a r-szu auge; devi 1 t. s-t wh c cb ruse henia*teb e e e theke an o Whichith articles maybe brought conveniently-and-rapidlm to swim 2 19 159 1 1.

(015?3-178) andztsuccessivelygsubmittedgto:;the gauge,;which will ei-ii'dicateflen a diaIireadablerzatsazglaiice tlie -di=ameter50f lithfificfintel' recesssatythe;endv surface -ef the f'articles, =theimeasurement. directly lta'ken .5 -byqthe gauge,finetheipresent illustrativesembqdiement of the inventions-beingsthe:depth ofeth e recess rand-means rbeingiprovided for :-;trans}atting this measurement FOL-depth ante; measurecme-nt ofidia-metenz-vmeans being still funther prq- =10 -vided;-foIr;- tlie1 readinggjof thegmeasurement-ef diameter; directlyiin -thqusandths of--an;inch, e sci-Again *een rallytw he devic m y z sef nlly emplnyed toEreadvthecl-iameters; of Legulaivshaped openings-of ;various kinds," by -means-of a cone- :p0int:ie u =pi in These and: other) ob ec s:end:-a YantaeeS wil :be a a e mmth folldwiu ldes u nr aken ztfl'gelififi i h -.t1;1e;-accompany.in dr win s: oi a' illustrative embediment of -the-invention,= and iii whichf rawin +w .1 t rr n i e rsect nel Yie ert ywi wee i c ;-embo i it e vi .g u l ness i i msitioii bf i u a e ther ezisz... fig rezis an flew at the t e e'q ffiaper a i ti niqr c ar iesso scrip en; if mm 3-is as de v ti a :see ktek n' h l ne 373 bf e- 261 9126. tar s: e er m i e F ur :i ;-i :ir mee er e pnt; l -sec- 'tien siniilar tofFigLl; ;bu hgwing the -ierovposih ure function of the gauge -l e d-i-eni ers ithe.ce z z .e tion; I qwn nth awin'gs-th e-ieewin ih u t i rrm i se ihe ifi P ri- .tiveeearts ffiheflvw e yih 129 c pi ea-b e q d e l wete s e, ii xb epe ii i In accordance with the-present invention,the

the arcuate movement of-the latter.

3 hollow base has interior bosses l4 inwardly and oppositely directed and providing bearings for a lever l5 of the third class in the sense that both arms of this lever extend in the same direction from the pivot or fulcrum and the effort is between the fulcrum and the resistance as will be later explained. The lever I5 is conveniently in the form of a platen and has a fulcrum pivot in the form of a pair of trunnions [6 having oppositely facing conical cavities ll therein which receive the conical journal ends l8 of pivot pintles H! which are in the form of headless screws threaded into tapped bores in the bosses 14. The bores 20 are shown open at the exterior of base ll so that another headless set-screw we may be threaded into each bore and a screwdriver or other tool may be inserted in a kerf 2i in the outer end of the set-screws I911. to fix the positions of the pintles for proper but free pivoting of the lever thereon.

Further in accordance with the present invention, the lever arms on the same side of the fulcrum already referred to are represented by respective sides of the lever platen, these sides being numbered 22 and 23 and terminating respectively at different distances from the fulcrum. Adjacent their ends the arms have palms 24 and 25 from which rise land pads or buttons 26 and 21 in each case. The distance from the center of the land button 26 to the pivot I! (which distance represents the length of the lever arm 22) is less than the distance from the center of the land button 21 to the lever pivot I! (which distance represents the length of the lever arm 23).

Still iurtherin accordance with the present invention, in contact with the land buttons 26 and 21 respectively are vertically reciprocable pins 28 and 29, which are arranged to follow the lever in its movement. For this purpose the gauge pin 28 is freely slidable in a smooth vertical bore 30 in the bushing 3i carried by the top wall of the casing H, the bushing having enlargement 32 which laps and projects above the casing platform I2 and providing a rostrum surface 33. The upper end of the gauge pin 28 is conoidal as at its nose 34 on a 60 degree taper in the present instance. At its lower end the gauge pin 28 is also conoidal as at 35 and rests on the button 26. Thus if the gauge pin 28 is pressed downwardly the lever [5 will be swung downwardly on its pivot fulcrum H, the lower end of the gauge pin sliding on the button 26 during such movement to compensate for the arcuate movement of the lever; that is, the vertical axis of the gauge pin will be displaced relatively toward the outer end of the arm 22 as the lever moves downwardly.

Accompanying this downward swinging movement of lever 15 under the influence of downward movement of gauge pin 28 is a consequent downward movement of the indicator pin 29 that in turn hasa conoidal lower end 36 in contact with the land button 21 of the arm 23. Here again,

' as the button 21 moves arcuately in the arcuate movement of the arm 23, the pointed lower end 36 of the indicator pin 29 is displaced relatively outwardly of the button 21, sliding on the surface of the button. In its downward movement the indicator pin 29 moves freely in the smooth bore 31 of a bushing 38 carried by the upper wall of the casing l I.

In the reverse or upward movement of the lever 15, the pointed lower ends of the pins 28 and 29 slide on the land buttons being displaced relatively inwardly of the lever arms in In all of these movements, the arms 22 and 23 being rigid with the lever platen, move together. The re duced or conical lower ends of the gauge and indicator pins minimize friction between them and the land buttons.

The lever l5 and with it the gauge pin 28 and indicator pin 29 are urged upwardly by a helical compression spring39 carried on a spring bolt 44 depending within the casing and screw-threaded into a tapped boss 4| on the unde'rface of the platform (2 as at 42. At its lower end the spring bolt has a head 43 against which the spring 39 abuts at its lower end, the upper end of the spring entering a counterbore 44 in the perfora= tion 45 in the platen of the lever l5 through which the spring bolt loosely passes, with suffi- -cient clearance to prevent interference with the lever.

lhe spring 39 is placed under compression by downward movement of the lever 15 and selective adjustment of such compression is provided by an adjusting screw 46 having a knurled knob 41 and which is screw-threaded into a tapped passageway 48 in the platform l2, the lower end of the adjusting screw 46 abutting a button 48 on the lever [5. In practice, the adjusting screw 43 may be screwed downwardly until the lever 15 is approximately horizontal, "as shown in Fig. 3 and in full lines in Fig. 1. The knurled head 41 affords a grip for the thumb and forefinger of the user for making this initial adjustment as well as subsequent adjustments which may be desirable as pointed out later. I

To permit the reading of the movements of th indicator pin 29, the latter is pressed upon by the plunger 50 of a standard gauge dial instrument indicated generally by the numeral 5|. The plunger 50 slides in a sleeve 52 carried by the instrument casing 53, through which the plunger projects above as at 54, the plunger sliding through the casing. The gauge instrument 5| contains the usual internal mechanism for such devices, which form no .part of the present invention and need not be here described, it being understood that such mechanism includes spring means for urging the plunger 50 outwardly, or in this case downwardly at all times against the in- -dicator pin 29 as at 55.

The gauge instrument 5| is shown mounted on a post'55 upstanding from the platform l2 and upon which is vertically slidable a link 51 having bifurc-ate jaws 58 through which pass a clamping screw 59 to fix the position of the link 51 vertically on the post 55. At its other end, the link 5'! is again bifurcate ina transverse direction by having the jaws 50 which gripthe instrument leg 6i extending rigidly from the back face of the gauge instrument casing 53, a clamping screw 62 again serving to fix the position of the leg 6| relatively to the link '51. This link and clamp provides a universal joint mounting adjustment for the instrument 5 l. V

The dial instrument 51 is arranged to read in thousandths of an inch and for this purpose has a thousandth hand 63 and a smaller hand 64, each arranged to swing about pivot points 65 and 65 respectively comprising the usual pointer hand spindles geared for rotation in response to reciprocation of the dial plunger 50. The hand 63 swings about the larger dial face figures 61 reading from zero and around the circle back thereto, one complete revolution of the hand 63 around this scale measuring a distance of .100 inch, the dial being scaled in increments of .010 inch. The smaller hand 64 is adapted to cooperate with the 15 of the article in vertical alignment with the conoidal upper end or nose 34 of the gauge pin 28. The article is then pressed down, with the nose 34 in the recess 15, until the end face 11 of the article '15 abuts the rostrum face 33. When this is done the lever i will have described a movement as indicated in Fig. 6 from its uppermost permissible position (permitted in, this instance by the screw 41) as indicated at 14 downwardly to the position of the lever shown in full lines at 18. The lower broken line 13 again represents the position to which the lever l5 would have moved downwardly to cause the dial to register zero. The line 18 therefore represents the position short of zero of the lever to which it is moved by the article 16 to be measured, as in Fig. 5, against the upward urge of spring 39. 7

At the same time, the lower end of the gauge pin 28 would have stopped short of zero a distance indicated by the double arrowed line 8|, and the lower end of the indicator pin point would have stopped short a distance indicated by the double arrowed line 82, against the downward urge of plunger 50.

Thus it will beunderstood that it is not the downward movement of the lever l5 which is measured (except indirectly by the dial instrument 5|, but rather it is the position of the lever upwardly from its zero position which is directly measured, or, in other words. the distance which the nose of the gauge pin would rise if the lever 15. were moved first to the lowermost or zero position, then the article '16 placed over the bore 30 for the gauge pin with the recess in register with the bore, and then the gauge pin allowed to rise under the influence of the spring 39 until stopped by the wall of the recess 15. If the article 16 moves the lever |5 downwardly from the possible upper limit of movement of the lever (as for example at M Fig. 6) to a position as shown at 18, this position would be incidental to movement of the lever I5 from the zero position as at 13 to the position as at 18. This would be represented by the rise of the nose 34 if it had a sharp apex, from a position flush with the rostrum surface 33 to a position coincident with the apex of the conical space of the recess 15, Since the nose 34 has a truncated apex but the truncation is exactly compensated for, the result is the same.

The distance (8|) of rise from the zero position of the nose 34 is equivalent to the altitude of the triangle defined by a cross-section of the recess 15 (Fig. 5). diameter 820 of the recess 15 at the end surface 11 of the article 16 which is coincident with the rostrum surface 33. This diameter 82a is equivalent to the distance 82 for the following reasons: By the laws of trigonometry 82a is equal to 1.1548 times the distance 8|, i. e., 2 tan. (.5774) times the distance 8|. The gauge device is, constructed, as already explained, so that the distance 82 is 1.1548 times the distance 8|. Therefore, the distance 82a is equivalent to the distance 82, both being 1.1548 times the distance 8|, 1. e. the distance of relative movement of the gauge pin upwardly from zero. Since the dial registers the distance 82 it also registers at the same time the diameter 82a. Thus if the distance 8|, or in other words the depth of the recess 15 should be .100 inch, then the distance 82a or the diameter of the recess at the face of the article would be .11548 inch, and the dial would directly indicate this measurement.

The base of this triangle is the If however as shown in dotted lines in Fig. 5;

V and as shown in Fig. 7,- the 60 conical recess in the article 16 should be deeper, as at 83, it would also be wider at the face of the cylinder. Consequently the nose 34 would go higher into the recess as at 84 and the gauge pin would move relatively upwardly from the zero position the distance as at 85, Figs. 5 and 7. This would cause the indicator pin to move relatively upward from the zero position a distance 88 equivalent to a diameter as indicated at 86c as shown in dotted lines in Fig. 5. If the distance 85 were, say, .150 inch then the distance 88 and 86a would be .173 inch, and the dial would so read.

As indicated in Fig. 8, the gauge device as here shown may be employed to measure the diameter as at 81 of a flared counterbore 88 (having a 60 taper or less) in a straight tube 89, provided the distance 81 is less than the over-all diameter of the gauge pin 28 so that the tube will abut the conical face of the nose 34 and provided further that the over-all diameter of the tube 89 be greater than the over-all diameter of the gauge pin so that the tube will abut the rostrum surface 33. Here the diameter 81 represents the base of a triangle the altitude of which is represented by the distance 81a, the ratio of which is as the ratio of 1.15481, and if the gauge pin 28 moves relatively from zero a distance of .100 inch into the tube 89 (i. e. the altitude 8111) then the diameter at 81 is .11548 inch.

As indicated in Fig. 9, the gauge device as here shown also maybe used to measure the diameter of a straight bore 90 in a tube 9| provided the bore 90 be less than the over-all diameter of the gauge pin and the over-all diameter of the tube 9| be greater than the over-all diameter of the gauge pin. Here the diameter of the bore 90 represents the base 92 of a triangle the altitude of which is represented by the distance 93, the ratio of which again is as the ratio of 1.15481, and if the gauge pin 28 moves a distance of .100 inch into the tube 9|, then the diameter of the bore 98 is .11548 inch, or the distance 92.

It will be apparent that if instead of 8| being a tube it were a rectangular member having a square opening instead of a cylindrical bore 90, the gauge device would also in the same way determine the cross-sectional dimension of the square opening.

If it were desired to work with conical recesses formed on angles other than 60, the gauge device could be modified by changing the ratio of the lengths of lever arms 22 and 23 of the lever I5 and by changing the upper end of the gauge pin to correspond with the angle to be worked with.

As shown in Fig. 10, assuming an article 94 having a conical recess 95 on an 82 included angle is desired to be measured. Here the nose 96 of the gauge pin 91 would be similarly an 82 conoid. The lever 98 (Fig. 11) would have its gauge pin 91 on an axis 99 and its indicator pin on an axis I80. Here the ratio of the distance from the fulcrum |0| to the axis 99 with reference to the distance from the fulcrum |8l to the axis I00 would be as the ratio of 1:1.7386, the latter being 2 x tan. 41 (.8693), and 41 being one-half of the included angle 82". The distance I82 would be to the distance H13 in the same ratio. Consequently, if the nose 96 moved relatively upwardly from the zero position the distance I02 or say .100 inch, then the dial instrument 5| would register .174 inch for the distance |03a or the diameter of the recess 95 at the face I04 of the article 94.

Again if it were desired to work with recesses 9:.E havingtae taper of 748, for example; as "shown in Figs 1-2, the gauge pin 1 05-wou-ld have a nose l 06 formed as a 4B: 'conoide Here: the lever arms would be reversed in the-sense-that -the gauge pin arm would be longer than the indicatorpin-arm 5- since the base of an isosceles-triangle having -an ang-lecfi 48"-- at its apexis shorter than the-altitude.- The ratiohoweverof the-base to the altitude is stil-l twice-the tangentofi one-:halfthe includedang-1e.- Consequently; for angles of 48 theratio of-the distancefrom thefulcrum l 01 to the gauge pin axis --l B8 :with-meference to thedistance from: the fulcrum '1 I31 ts the indicator pinlaxisl 09= would be as the-ratio-oi, 1 tangent-24 (.4452) or-.8904 Thus-,ifithe'gaugepin were to move :a' relativedistance ofwl5o-inch 'asflat Hfl- (Figs: Hand 13-), the indicator-pin would move-arrelative distanceas at Ill-(Fig. -l3 )and the? dial instrument would--register 133 inch, whichwould-bethe diameterl l la. I I It will bemnderstocd that tubes-having a flared l cou-n-ter bore on" an 8-2 taper-or--less-.could--have the-:diameter ofthe counter-boreat the-endpf the tube'measu-redby thepresent device modified 4 asrshown in-Fi g; 10,- and-that tubeshavingeaflared counter-boreonva 48 taper orfl less :could havethediameter ofi-the-counter-bore at the.- endrofthetube-measured by the present device modified as shown in Fig.. 127- Thesemodificationsrwouldiunction similarlyto the-functionof the device as here specifically shown arrangedfor 60:or 'less-angles-as in 'Figs;--l to-8 inclusive.

Furthermore, for measuringa tubes having a straight bore asin Fig.,-9,-the modifications shown in Figs: l0 -to 13 :could be used- -just---as well --as the device-as :shown in Figs: 1 ate: 9 inclusive, pro? vided :onlythat the inner :diameter of the Qbore beless-than the over-all-diameter of'the gauge pin and that the outer diameter ofthe tubebe greater than-the over all diameter o-f the gaugepm" 7 It Will be-understood-: that-adaptations of lthe device'to other angles than thoseherespecifically illustrated :may be readily made following .-.the characteristicfeaturesof the present inventio'iras here exemplified. v

For example; the-principle eir-utilizing:- a trig-.-. onometric function -ofan angle ofthe a triangle in predetermining thearrangement of-means-for translating: the distance-of movement of agauge. pin-along one element: of thestriangle other than thef-base of the triangIems-here illustrated, ;-be employed by -haVi-ng.the-gauge pin move along an element of thetriangle other than the alt-itude,.'v as here specifically described, and -in stead, alongone'of thesides other than the base 5.; andwhichside would be' the hypotenuse of a right-angle triangle of which the base would be one-half of the diameter to be measured and the ratio of the diameter to be measured to the hypotenuse would be as the ratio-0f twice the ,9 sine of one-half the included angle' atthe apex to 1.

The invention is not intended to be limited to details of construction shown for purposes of exemplificati'on. Furthermcrejit is not essential :5

allufeature's ofthe device be used conjointly as. various." combinations or sub-combinations may at "times be "advantageously:employed? Such'changes may be made -"as 'fa-ll withinthe scope of the appended claims without die-part 7 ing.v from the invention;

The invention'havingbeen described; what is here claimed is:

l. A-gauge device embodying a base, alever earriedrby. the base comprisinga platema fixed 7s fulcrum -for-said lever, said lever comprising integrallytherewith as side s o f saidnplateii a=gaugepin arm and an indicator pin -arm,-saidiarxns beingonthe same side of said fulcrum rigiduwith said lever and having -a common 'pivotpoint eomcidentlwitli "said fulcrum,- :gauge pin .and 1 an indicator pin. arranged slidablv'iin th'elbase 1m. paralleland for reciprocationimmatures axes. respectively; said 'pin's' 'each having an inner engagement with the gauge-pin arm and indicator pin arm respectively by anti-friction 'contact ion each arm-wherebythe pins maintaintheirparreciprocable throughsaid surface and having-ea con-oidal l. termination, an indicator pin being} reciprocable in parallelism with-the gauge pirrminecontact with said le'ver, sa-idjpinslceinglrecipro cable on axes respectively. spaced '.rrqm s id m1-i crum at distances related 'in'lng'th in'the' ratio of '1 to twice the trigonometric t ngent o'fteehalf the included angle at "the conoidal-Tt e'rt'n'iirc's-I tion,'means'urging the gaugefpin'point in one ment plunger urging the indicator" pin in the oppositedirectioni' I 3. In a gauge device for measuring tl'ie'dia eters of recesses, means comprisin'g a consider gauge pin enterable into therecess with" it dal wall in engagement'with thewallof'th re a gauge instrument, and means"fof translating. the distance of entrance of, the gaug'e 'piriiizito the recess into measurement on the instru'meiitcf the diameter of th'erecess; said last mentioned means employing the principle of the trigono f metric relationship of said diameter to saididis tance' and including: a 1 pair of, interconnected levers, the levers being related' 'in length res tivelyj'in'theratio of 1 to'twicethetangentiof one=half the included angle at the apex? 4. Inia gauge device of the"classjdescribedffdf measuring the diameters of recesses; the com: binationcomp'risinga' gauge pin havingfa'c'onoi daritermmation; a gauge instrument," and-lever means "for translating "the distancef of entrance: of the 'conoidalterminati'on 0f thexgausepin ifitd." the recess into measurement 'on the instrument of 'thediametr of the'recess, said lever means including'a painof rigidly connected lever arms havingacommon pivot and being of different lengths "and extending in a common plane from; their common pivot,.one ofsaid levers beinglar ranged to-be moved a predetermined distance inresponse to a-given distance of" movement of thegauge pin'into the recess limited bywthe wall=ofthesrecess and the other lever beingarranged to move a predetermined distanceuponmovement, of the first mentioned lever to actuate the instrua .ment,-the levers .being related-in length in the ratio of 1 to twice the trigonometrictangent of"- an -angleof a right-angle triangle one *sideof which. equal to the distance of movement- 0f to one-halfthe-diameter of therecess.

5. In a gauge device of theclass described for measuring the diameters of recesses, the'com: bination comprising, a gauge pin havinga conoidal termination, a gauge instrument, and lever means for translating the distance of entrance of the conoidal termination of the gauge pin into the recess into measurement on the instrument of the diameter of the recess, said lever means including a pair of rigidly connected lever arms having a'commcn pivot and being of different lengths and extending in a common plane in the same direction from their common pivot, one of said levers being arranged to be moved apredetermined distance in response to a given distance of movement of the gauge pin into the recesslimited by the wall of the recess and the other lever being arranged to move a, predetermined distance upon movement of the first mentioned lever 'to actuate theinstrument, the levers being related in length in the ratio of 1 to twice the tangent of an angle of a right-angle triangleone side of which is equal to the distance of movement of the gauge pin and another side of which is equal to one-half the diameter of the recess. V, l

6. In a gauge device of, the .class described for measuring the diameters of recesses, the combination, comprising, a gauge pin having a conoidal termination, a gauge instrument, and lever means for translating the distance of entrance of the conoidal termination of the gauge pin into the recess into measurement on the instrument of the diameter of the recess, said lever means including a pair of interconnected levers of difi'erent lengths, one of said levers being arranged to be moved a predetermined distance in response to a given distance of movement of the gauge pin into the recess limited by the wall of the recess and the other lever being arranged to move a predetermined distance upon movement of the first mentioned lever to actuate the instrument, the levers being related in length in the ratio of 1 to twice the tangent of an angle of a right-angle triangle one side of which is equal to the distance of movement of the gauge pin and another side of which is equal to one-half the diameter of the recess.

'7. In a gauge device of the class described for measuring the diameters of recesses, the combination, comprising, a gauge pin having a conoidal termination, a gauge instrument, and lever means for translating the distance of entrance of the conoidal termination of the gauge pin into the recess into measurement on the instrument of the diameter of the recess, said lever means including a pair of interconnected levers of different lengths extending on the same side of a common fulcrum, one of said levers being arranged to be moved a predetermined distance in response to a given distance of movement of the gauge pin into the recess limited by the wall of the recess and the other lever being arranged to move a predetermined distance upon movement of the first mentioned lever to actuate the instrument, the levers being related in length in the ratio of 1 to twice the trigonometric tangent of an angle of a right angle triangle one side of which is equal to the distance of movement of the gauge pin and another side of which is equal to one-half the diameter of the recess.

8. A gauge device embodying a lever, a fulcrum for said lever, said lever comprising a gauge pin arm and an indicator pin arm, said arms being rigid with said lever and of different lengths, the length of the indicator pin arm being to the length of the gauge pin arm as twice the tangent of a given angle to 1, a gauge pin and an indicator pin arranged in parallel and for reciprocation along their axes respectively, said pins each having an inner engagement with the gauge pin arm and indicator pin arm respectively by a sliding contact on each arm whereby the pins maintain their parallelism while in reciprocation in engagement with the arms, an outer conoidal termination on the gauge pin for insertion into a recess to be measured, a dial plunger in spring pressed engagement with the indicator pin outer end, a dial hand associated with said plunger for indicating the distance of travel of said plunger, resilient means urging the lever in a direction opposing the plunger spring, and means for setting the lever and pins at zero position.

9. A gauge device embodying a base, a lever pivoted on the base and comprising a platen, said lever including integrally therewith as sides of said platen a gauge pin arm and an indicator pin arm, said arms being of different lengths on the same side of said fulcrum rigid with said lever and having a common pivot point, a gauge pin and an indicator pin carried by the base responsive to movements of said arms respectively, and a dial instrument responsive to movement of the indicator pin, wherein the platen is perforated and the base carries a spring post passing through said perforations, and a spring presses at one end against the post and at its other end against the platen.

10. A gauge device embodying a lever, a fulcrum for said lever, said lever comprising a gauge pin arm and an indicator pin arm, said arms being rigid with said lever and of different lengths, the length of the indicator pin arm being to the length of the gauge pin arm as twice the tangent of a given angle to 1, a gauge pin and an indicator pin arranged in parallel and for reciprocation along their axes respectively, said pins each having an inner engagement with the gauge pin arm and indicator pin arm respectively by a sliding contact on each arm whereby the pins maintain their parallelism while in reciprocation in engagement with the arms, an outer conoidal termination on the gauge pin for insertion into a recess to be measured, a dial plunger in spring pressed engagement with the indicator pin outer end, a dial hand associated with said plunger for indicating the distance of travel of said plunger, resilient means urging the lever in a direction opposing the plunger spring, and an adjustable stop member for limiting movement of the lever in the direction it is urged by said resilient means.

HUGO A. HAMZERLY. SEYMOUR H. WRIGHT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 181,809 Williams Sept. 5, 1876 1,290,434 Walter Jan. 7, 1919 1,485,154 Aldeborgh Feb. 26, 1924 1,648,428 Stacy Nov. 8, 1927 2,124,014 Street July 19, 1938 2,210,560 Allen et a1 Aug. 6, 1940 2,304,460 Kelleher Dec. 8, 1942 2,399,012 Farrance Apr. 23, 1946 FOREIGN PATENTS Number Country Date 591,332 Germany Jan. 19, 1934 

